I think you are fooling yourself if you think that a closed system like Jolla (apparently) will let the community have any saying about the core functionality. The core functionality is more tied to HW and UX, and ecosystem.

You can roll your own distribution of Android, no problems. The main hurdle is to make a viable ecosystem. Amazon does it.

Back in the days I was a fan of BeOS. A really excellent OS. An open source clone exist today. BeOS was eventually scrapped because if I remember correctly "the time of new operating systems has ended" (or something like that). What does that mean? It means that even though you create the most perfect of operating systems it will not live, because OS is no longer a deciding factor. That's why Linux have never made it into desktops, and why Mac has grown in popularity. In other words - ecosystem is the deciding factor.

If Jolla had some cool new ideas regarding ecosystems, they maybe would have a chance (and a much better chance if they forked Android). If they had some cool stuff that made the ecosystem irrelevant (cool HW, Alien Dalvik maybe), they would have a chance. So far I have seen nothing. It seems as though they just want to continue where they left off regardless of how the world around them looks. That is no recipe for success.

Untill Jolla comes with some more relevant info, I will stop now